Under the auto-enrolment scheme, employees contribute a portion of their wages into their pension, with contributions also coming from employers as well as tax relief.

Minimum contributions are being gradually phased upwards, so that from April 6 2019 they will increase to 8% of qualifying earnings, of which a minimum of 3% must come from the employer. Currently, the minimum contribution rate is 2%, with at least 1% coming from the employer.

Scottish Widows' Workplace Pensions report said that despite this lack of awareness, only 3% of people said they would opt out when their contributions increased.

More than a quarter (27%) of people said they cannot save any more into their workplace pension due to financial pressures.

David Holton, director of pension propositions at Scottish Widows, said: "T he industry and employers alike need to continue encouraging all workers by providing them with ongoing support on the benefits of being more engaged with longer term savings."

More than 5,000 people took part in the research in April.

Automatic enrolment started in 2012 to head off fears of an old age savings crisis. The scheme is being rolled out gradually, with the largest employers with more experience of pensions having come on board first and the smallest employers now being brought into the initiative.

Workers are generally eligible for automatic enrolment if they are at least 22 years old and under state pension age, earning over £10,000 a year and work, or usually work, in the UK.

So far, the initiative has been seen as a success, with a higher-than-expected rate of nine in 10 employees staying in the scheme, rather than opting out. But concerns have also been raised that people should not expect that just making minimum contributions will give them the standard of retirement that they would want.

More than 6.7 million workers have been automatically enrolled so far, and eventually around 10 million people are expected to be newly saving or saving more as a result of the scheme.

A spokeswoman at the Department for Work and Pensions (DWP) said: " We know that people need to save more for retirement which is why contributions will be increasing over the coming years and we are working closely with industry and employers to get this message out."